Boronic Acid functionalized core-shell polymer nanoparticles prepared by distillation precipitation polymerization for glycopeptide enrichment

Study on the creation of boronate affinity-based oriented imprinted silica nanoparticles and their selective recognition toward glycopeptide antibiotics in food and water

Taking into account the drug resistance of antibiotics, teicoplanin has been banned in the veterinary field. Also, it brings threat to people's health when they eat foods containing teicoplanin residue. In addition, the abuse of teicoplanin in humans and food animals also poses a potential risk to water. Therefore, it is crucial to purify teicoplanin from food before quantifying its amount. In this study, researchers employed boronate affinity-based controlled oriented surface imprinting technique to produce molecularly imprinted polymers (MIPs) for the isolation of teicoplanin. The 3-fluoro-4-formylphenylboronic acid-functionalized silica nanoparticle substrate was first used as the supporting material for immobilizing teicoplanin. Next, the substrate surface was coated with an imprinting coating whose thickness could be controlled, produced through the self-copolymerization of dopamine and m-aminophenylboronic acid (APBA) in water. After the template was removed, 3D cavities that matched the template were created in the imprinting layer. The prepared teicoplanin-imprinted silica nanoparticles exhibited several significant satisfactory results such as good specificity, high binding capacity (46.9 ± 2.3 mg g-1), moderate binding constant ((5.46 ± 0.18) × 10-5 M-1), fast kinetics (8 min) and low binding pH (pH 5.0) toward teicoplanin. The teicoplanin-imprinted silica nanoparticles could still be reused after seven cycles of adsorption-desorption, which indicated a high chemical stability. In addition, recoveries of the proposed method for teicoplanin at three spiked levels in milk and water ranged from 91.8 to 105.6% and 92.3 to 97.4%, respectively. The teicoplanin-imprinted silica nanoparticles are capable of identifying the target teicoplanin in real samples in a simple, fast, selective and efficient manner.

Synthesis of Boronate Affinity-Based Oriented Dummy Template-Imprinted Magnetic Nanomaterials for Rapid and Efficient Solid-Phase Extraction of Ellagic Acid from Food

Ellagic acid (EA) is a natural polyphenol and possesses excellent in vivo bioactivity and antioxidant behaviors, which play an important role in the treatment of oxidative stress-related diseases, such as cancer. Additionally, EA is also known as a skin-whitening ingredient. The content of EA would determine its efficacy. Therefore, the accurate analysis of EA content can provide more information for the scientific consumption of EA-rich foods and cosmetics. Nevertheless, the analysis of EA in these samples is challenging due to the low concentration level and the presence of interfering components with high abundance. Molecularly imprinted polymers are highly efficient pretreatment materials in achieving specific recognition of target molecules. However, the traditional template molecule (EA) could not be absolutely removed. Hence, template leakage continues to occur during the sample preparation process, leading to a lack of accuracy in the quantification of EA in actual samples, particularly for trace analytes. In addition, another drawback of EA as an imprinting template is that EA possesses poor solubility and a high price. Gallic acid (GA), called dummy templates, was employed for the synthesis of MIPs as a solution to these challenges. The approach used in this study was boronate affinity-based oriented surface imprinting. The prepared dummy-imprinted nanoparticles exhibited several significant advantages, such as good specificity, high binding affinity ((4.89 ± 0.46) × 10-5 M), high binding capacity (6.56 ± 0.35 mg/g), fast kinetics (6 min), and low binding pH (pH 5.0) toward EA. The reproducibility of the dummy-imprinted nanoparticles was satisfactory. The dummy-imprinted nanoparticles could still be reused even after six adsorption-desorption cycles. In addition, the recoveries of the proposed method for EA at three spiked levels of analysis in strawberry and pineapple were 91.0-106.8% and 93.8-104.0%, respectively, which indicated the successful application to real samples.

The preparation of a boronate affinity-based controlled oriented imprinting coating on a silica nanoparticle surface for the separation and purification of shikimic acid in herbal medicine

Shikimic acid (SA) is one of the most effective drugs against the A (H1N1) virus and has high medicinal value. Additionally, it has the ability to generate non-toxic herbicides and antimicrobial medications. The extraction from plants has proven to be the main route of production of SA with economic benefits and environmental efficiency. Therefore, it is necessary to perform purification of SA from these herbal medicines before quantifying it. In this study, researchers employed a boronate affinity-based controlled oriented surface imprinting technique to produce molecularly imprinted polymers (MIPs) as highly effective solid phase extraction (SPE) adsorbents for the isolation and purification of SA. 3-Fluoro-4-formylphenylboronic acid functionalized silica nanoparticles were used as supporting materials for immobilizing SA. Poly(2-anilinoethanol) with a higher hydrophilic domain can be used as an effective imprinting coating. The prepared SA-imprinted silica nanoparticles exhibited several significant results, such as good specificity, high binding capacity (39.06 ± 2.24 mg g-1), moderate binding constant (6.61 × 10-4 M-1), fast kinetics (8 min) and low binding pH (pH 5.0) toward SA. The replication of SA-imprinted silica nanoparticles was deemed satisfactory. The SA-imprinted silica nanoparticles could be still reused after seven adsorption-desorption cycles, which indicated high chemical stability. In addition, the recoveries of the proposed method for SA at three spiked level analysis in star aniseed and meadow cranesbill were 96.2% to 109.0% and 91.6% to 103.5%, respectively. The SA-imprinted silica nanoparticles that have been prepared are capable of identifying the target SA in real herbal medicines. Our approach makes sample pre-preparation simple, fast, selective and efficient.

Systematic characterization of extracellular glycoproteins using mass spectrometry

Surface and secreted glycoproteins are essential to cells and regulate many extracellular events. Because of the diversity of glycans, the low abundance of many glycoproteins, and the complexity of biological samples, a system-wide investigation of extracellular glycoproteins is a daunting task. With the development of modern mass spectrometry (MS)-based proteomics, comprehensive analysis of different protein modifications including glycosylation has advanced dramatically. This review focuses on the investigation of extracellular glycoproteins using MS-based proteomics. We first discuss the methods for selectively enriching surface glycoproteins and investigating protein interactions on the cell surface, followed by the application of MS-based proteomics for surface glycoprotein dynamics analysis and biomarker discovery. We then summarize the methods to comprehensively study secreted glycoproteins by integrating various enrichment approaches with MS-based proteomics and their applications for global analysis of secreted glycoproteins in different biological samples. Collectively, MS significantly expands our knowledge of extracellular glycoproteins and enables us to identify extracellular glycoproteins as potential biomarkers for disease detection and drug targets for disease treatment.

Catalyst- and Stabilizer-Free Rational Synthesis of Ionic Polymer Nanoparticles in One Step for Oil/Water Separation Membranes

Ionic polymer nanoparticles (IPNs) were synthesized in one pot by quaternization precipitation polymerization (QPP) as a novel polymerization technique. QPP eliminated the usage of high-cost ionic monomers and reduced the number of steps for the preparation of IPN. The monomers 2-(dimethylamino)ethyl methacrylate (DMAEMA) and 4-vinylbenzyl chloride (VBC) polymerized in the presence of azobisisobutyronitrile (AIBN) and underwent quaternization simultaneously, which yielded ionic poly(DMAEMA-co-VBC) nanoparticles in one step with the size of 50-80 nm without any stabilizer and catalyst. Similarly, 4-vinylpyridine (VP) and VBC polymerized in the presence of AIBN and underwent quaternization simultaneously, which yielded ionic poly(VP-co-VBC) nanoparticles in one step with the size of 70-90 nm without any stabilizer and catalyst. The as-synthesized IPN was further utilized for the fabrication of hydrophilic nanocomposite ultrafiltration membranes for oil/water separation. Fabricated hybrid membranes were characterized and studied for oil rejection properties. It exhibited an oil rejection of >96% with a pure water permeability of 219 L/m² h bar.

Precipitation Polymerization: A Powerful Tool for Preparation of Uniform Polymer Particles

Precipitation polymerization (PP) is a powerful tool to prepare various types of uniform polymer particles owing to its outstanding advantages of easy operation and the absence of any surfactant. Several PP approaches have been developed up to now, including traditional thermo-induced precipitation polymerization (TRPP), distillation precipitation polymerization (DPP), reflux precipitation polymerization (RPP), photoinduced precipitation polymerization (PPP), solvothermal precipitation polymerization (SPP), controlled/‘‘living’’ radical precipitation polymerization (CRPP) and self-stabilized precipitation polymerization (2SPP). In this review, a general introduction to the categories, mechanisms, and applications of precipitation polymerization and the recent developments are presented, proving that PP has great potential to become one of the most attractive polymerization techniques in materials science and bio-medical areas.

Highly efficient separation and enrichment of polyphenols by 6-aminopyridine-3-boronic acid-functionalized magnetic nanoparticles assisted by polyethylenimine

Polyphenols have found a lot of therapeutic effects and potential applications such as antioxidant, anti-inflammatory, mutant resistance, immunosuppressant and anti-tumor properties. They can be divided into five main classes, namely flavonoids, phenolic acids, stilbenes, lignans, and others. Thus, the content detection of polyphenols in real samples such as fruit juice and tea is of great significance. Due to the presence of complex interfering components in actual samples, separation and enrichment of polyphenols prior to analysis is key. Therefore, it is quite necessary to establish a simple, low-cost and efficient purification method for cis-diol-containing polyphenols from real samples. Boronate affinity materials are able to reversibly bind cis-diol-containing compounds by forming a five- or six-membered boronic cyclic ester in aqueous media. However, conventional boronate affinity materials exhibited low binding capacity and high binding pH. In this study, the polyethyleneimine (PEI)-assisted 6-aminopyridine-3-boronic acid functionalized magnetic nanoparticles (MNPs) were developed to capture efficiently cis-diol-containing polyphenols under neutral condition. PEI was applied as a scaffold to amplify the number of boronic acid moieties. While 6-aminopyridine-3-boronic acid was used as an affinity ligand due to low pK a value and excellent water solubility toward polyphenols. The results indicated that the prepared boronic acid-functionalized MNPs provided high binding capacity and fast binding kinetics under neutral conditions. In addition, the obtained MNPs exhibited relatively high binding affinity (K d ≈ 10-4 M), low binding pH (pH ≥ 6.0) and tolerance of the interference of abundant sugars.

Polyamidoamine dendrimer-assisted 3-carboxybenzoboroxole-functionalized magnetic nanoparticles for highly efficient capture of trace cis-diol-containing biomacromolecules

Boronate affinity materials have attracted more and more attention in recent years due to their highly selective capture of cis-diol-containing biomacromolecules.

Efficient synthesis of boronate affinity-based catecholamine-imprinted magnetic nanomaterials for trace analysis of catecholamine in human urine

Catecholamines, a class of cis-diol-containing compounds, play a major role in the central nervous system.

Maximizing Depth of PTM Coverage: Generating Robust MS Datasets for Computational Prediction Modeling

Post-translational modifications (PTMs) regulate complex biological processes through the modulation of protein activity, stability, and localization. Insights into the specific modification type and localization within a protein sequence can help ascertain functional significance. Computational models are increasingly demonstrated to offer a low-cost, high-throughput method for comprehensive PTM predictions. Algorithms are optimized using existing experimental PTM data, thus accurate prediction performance relies on the creation of robust datasets. Herein, advancements in mass spectrometry-based proteomics technologies to maximize PTM coverage are reviewed. Further, requisite experimental validation approaches for PTM predictions are explored to ensure that follow-up mechanistic studies are focused on accurate modification sites.

Post-synthesis modification of covalent organic frameworks for ultrahigh enrichment of low-abundance glycopeptides from human saliva and serum

In this study, a novel type of covalent organic framework (COF) material rich in boronic acid sites was prepared through post-synthesis modification (TbBD@PEI@Au@4-MPBA). The surface of COF material had abundant carboxylic acid groups, which could bind a large amount of polyethyleneimine (PEI) through electrostatic interaction. At the same time, the amino groups on the PEI can be grafted with Au nanoparticles (Au NPs) in situ, and then 4-mercaptophenylboronic acid (4-MPBA) was modified by the reaction of Au and sulfhydryl groups. The massive grafting of boronic acid groups made the material's enrichment effect on glycopeptides expected. The results of experiments indicated that the composite material has high sensitivity (5 amol μL^-1) and selectivity (1:1000). In addition, the material has outstanding stability and reusability, with a load capacity of about 100 mg g^-1 and a recovery of 99.3 ± 2.2%. What's more, after enriched by TbBD@PEI@Au@4-MPBA, 56 endogenous glycopeptides from fresh human saliva were detected by MALDI-TOF MS, 56 unique glycopeptides corresponding to 31 glycoproteins from human saliva and 513 unique glycopeptides corresponding to 208 glycoproteins from serum of throat cancer patient were detected by nano-LC-MS/MS, respectively, which was expected to be applied to glycoproteomics research.

Glutathione-functionalized two-dimensional cobalt sulfide nanosheets for rapid and highly efficient enrichment of N-glycopeptides

Protein glycosylation plays pivotal role in a variety of biological processes and has association with many diseases. The highly efficient glycopeptide enrichment is essential for the mass spectrometry-based glycoproteome research to reduce interference from non-glycopeptides. In this study, novel glutathione-functionalized two-dimensional cobalt sulfide nanosheets (Co-S@Au-GSH) were synthesized for rapid and highly effective enrichment of glycopeptides. By using this nanomaterial, 34 and 21 N-glycopeptides were effectively captured from human serum immunoglobulin G (IgG) and horseradish peroxidase (HRP) digests, respectively. In addition, the Co-S@Au-GSH showed remarkable performance in N-glycopeptide extraction with high selectivity (HRP: BSA = 1:500), low limit of detection (0.5 fmol/μL), high binding capacity (150 mg/g), good reusability, and great robustness. Moreover, it was successfully applied in complex serum samples, demonstrating its excellent enrichment performance. These results indicated that this nanomaterial has great potential in complicated practice samples in glycoproteome determination.

Synthesis, parameters, properties and applications of responsive molecularly imprinted microgels: a review

Responsive molecularly imprinted microgels (MIGs) have gained a lot of interest due to their responsive specificity and selectivity for target compounds. Study on MIGs is rapidly increasing due to their quick responsive behavior in various stimuli like pH and temperature. MIGs show unique property of morphology control on in-situ synthesis of nanoparticles in response of variation in reactant concentration. Literature related to synthesis, parameters, characterization, applications and prospects of MIGs are critically reviewed here. Range of templates, monomers, initiators and crosslinkers are summarized for designing of desired MIGs. This review article describes effect of variation in reactants combination and composition on morphology, imprinting factor and percentage yield of MIGs. Hydrolysis of similar templates using MIGs is also described. Relation between percentage hydrolysis and hydrolysis time of targets at different temperatures and template:monomer ratio is also analyzed. Possible imprinting modes of ionic/non-ionic templates and its series are also generalized on the basis of previous literature. MIGs are investigated as efficient anchoring vehicles for adsorption, catalysis, bio-sensing, drug delivery, inhibition and detection.

Antibody-Free Hydrogel with the Synergistic Effect of Cell Imprinting and Boronate Affinity: Toward the Selective Capture and Release of Undamaged Circulating Tumor Cells

The selective and highly efficient capture of circulating tumor cells (CTCs) from blood and their subsequent release without damage are very important for the early diagnosis of tumors and for understanding the mechanism of metastasis. Herein, a universal strategy is proposed for the fabrication of an antibody-free hydrogel that has a synergistic effect by featuring microinterfaces obtained by cell imprinting and molecular recognition conferred by boronate affinity. With this artificial antibody, highly efficient capture of human hepatocarcinoma SMMC-7721 cells is achieved: as many as 90.3 ± 1.4% (n = 3) cells are captured when 1 × 10⁵ SMMC-7721 cells are incubated on a 4.5 cm² hydrogel, and 99% of these captured cells are subsequently released without any loss of proliferation ability. In the presence of 1000 times as many nontarget cells, namely, leukaemia Jurkat cells, the SMMC-7721 cells can be captured with an enrichment factor as high as 13.5 ± 3.2 (n = 3), demonstrating the superior selectivity of the artificial antibody for the capture of the targeted CTCs. Most importantly, the SMMC-7721 cells can be successfully captured even when spiked into whole blood, indicating the great promise of this approach for the further molecular characterization of CTCs.

Efficient synthesis of boronate affinity-based chlorogenic acid-imprinted magnetic nanomaterials for the selective recognition of chlorogenic acid in fruit juices

Chlorogenic acid (CGA), a cis-diol-containing compound, can exhibit anti-inflammatory, antiviral, antimicrobial and anti-oxidation properties.

The challenges of glycan recognition with natural and artificial receptors

Glycans - simple or complex carbohydrates - play key roles as recognition determinants and modulators of numerous physiological and pathological processes. Thus, many biotechnological, diagnostic and therapeutic opportunities abound for molecular recognition entities that can bind glycans with high selectivity and affinity. This review begins with an overview of the current biologically and synthetically derived glycan-binding scaffolds that include antibodies, lectins, aptamers and boronic acid-based entities. It is followed by a more detailed discussion on various aspects of their generation, structure and recognition properties. It serves as the basis for highlighting recent key developments and technical challenges that must be overcome in order to fully deal with the specific recognition of a highly diverse and complex range of glycan structures.

Efficient enrichment of glycopeptides by supramolecular nanoassemblies that use proximity-assisted covalent binding

Mass spectrometry (MS)-based analysis of glycoproteins and glycopeptides requires selective separation strategies to eliminate interferences from more abundant non-glycosylated biomolecules. In this work, we describe a two-phase liquid-liquid extraction method using supramolecular polymeric nanoassemblies that can selectively and efficiently enrich glycopeptides for enhanced MS detection. The polymeric nanoassemblies are made selective for glycopeptides via the incorporation of hydrazide functional groups that covalently bind to glycans. The enrichment efficiency is further enhanced via the incorporation of acidic functional groups that lead to a proximity-assisted catalysis of the hydrazide-glycan conjugation reaction. Our results further demonstrate the value of designer supramolecular nanomaterials for the selective enrichment of modified peptides from complicated mixtures.

Site-specific N-glycosylation of HeLa cell glycoproteins

We have characterized site-specific N-glycosylation of the HeLa cell line glycoproteins, using a complex workflow based on high and low energy tandem mass spectrometry of glycopeptides. The objective was to obtain highly reliable data on common glycoforms, so rigorous data evaluation was performed. The analysis revealed the presence of a high amount of bovine serum contaminants originating from the cell culture media - nearly 50% of all glycans were of bovine origin. Unaccounted, the presence of bovine serum components causes major bias in the human cellular glycosylation pattern; as is shown when literature results using released glycan analysis are compared. We have reliably identified 43 (human) glycoproteins, 69 N-glycosylation sites, and 178 glycoforms. HeLa glycoproteins were found to be highly (68.7%) fucosylated. A medium degree of sialylation was observed, on average 46.8% of possible sialylation sites were occupied. High-mannose sugars were expressed in large amounts, as expected in the case of a cancer cell line. Glycosylation in HeLa cells is highly variable. It is markedly different not only on various proteins but also at the different glycosylation sites of the same protein. Our method enabled the detailed characterization of site-specific N-glycosylation of several glycoproteins expressed in HeLa cell line.

Preparation of a thickness-controlled Mg-MOFs-based magnetic graphene composite as a novel hydrophilic matrix for the effective identification of the glycopeptide in the human urine

The highly effective analysis of glycopeptides from complex biological samples is an attractive and critical topic all the time. In this study, a novel thickness-controlled hydrophilic Mg-metal organic frameworks (Mg-MOFs) coating-functionalized magnetic graphene composite (MagG@Mg-MOFs-1C) was prepared for the capture of the glycopeptides. The as-synthesized composite exhibits an ultralow limit of detection (0.1 fmol μL-1), a perfect size-exclusion effect (HRP digests/BSA protein/HRP protein, 1 : 500 : 500, w/w/w), and a high binding capacity (150 mg g-1), satisfying reusability and high recovery in the recognition of glycopeptides due to its outstanding characteristics including strong magnetic property, large surface area (617 m2 g-1), plenty of affinity sites, and excellent hydrophilicity. Furthermore, the MagG@Mg-MOFs-1C composite was successfully applied to selectively enriched glycopeptides in human urine. More excitingly, 406 N-glycosylation peptides corresponding to 185 glycoproteins were identified in the urine of the bladder cancer patients, in which these identified glycoproteins include the potential biomarkers (α-2-macroglobulin, complement C4-B, and α-1-antitrypsin) for the bladder cancer. This study suggests that the hydrophilic porous MOFs-functionalized composite has a great potential in the large-scale characterization of the low-abundance biomolecules in urine, opening a new avenue for the rapid and convenient diagnosis of the disease.

Branched polyethyleneimine-assisted 3-carboxybenzoboroxole improved Wulff-type boronic acid functionalized magnetic nanoparticles for the specific capture of cis-diol-containing flavonoids under neutral conditions

Flavonoids have shown a variety of biological activities such as antimicrobial, antibacterial, antifungal, antiviral, antiinflammatory, antitumor, antiatherogenic, and antihyperglycemic activities. A lot of important flavonoids contain cis-diols such as rutin (Ru), quercetin (Qu), luteolin (Lu), myricetin (Myr) and baicalein (Ba) and so on. It is necessary to establish a simple, low-cost and efficient purification method for cis-diol-containing flavonoids from plant extracts. Boronate affinity materials are able to reversibly bind the cis-diols via boronic acids by forming a five- or six-membered boronic cyclic ester in aqueous media. However, conventional boronate affinity materials have to be used in alkaline media, which can lead to the oxidation of cis-diols in compounds. In this study, the polyethyleneimine (PEI)-assisted 3-carboxybenzoboroxole-functionalized magnetic nanoparticles (MNPs) were prepared to achieve efficient capture of cis-diol-containing flavonoids under neutral conditions. Branched PEI was applied as a scaffold to amplify the number of boronic acid moieties, while 3-carboxybenzoboroxole, exhibiting high affinity and excellent water solubility toward flavonoids, was used as an affinity ligand. The prepared boronate affinity MNPs exhibited high binding capacity and fast binding kinetics (equilibrium in 3 min) under neutral conditions. In addition, the obtained boronate affinity MNPs exhibited high binding affinity (K_d ≈ 10⁻⁴ M), low binding pH (pH ≥ 6.0) and tolerance of the interference to abundant sugars.

Flavonoids have shown a variety of biological activities such as antimicrobial, antibacterial, antifungal, antiviral, antiinflammatory, antitumor, antiatherogenic, and antihyperglycemic activities.

A facile and general approach for the preparation of boronic acid-functionalized magnetic nanoparticles for the selective enrichment of glycoproteins

Biomedical applications and biomarkers for early clinical diagnostics and the treatment of diseases demand efficient and selective enrichment platforms for glycoproteins.

Pyridine boronic acid-polyoxometalate based porous hybrid for efficient depletion of high abundant glycoproteins in plasma

A porous hybrid, namely PW₁₂@TiO₂-Si(Et)Si/Pba, is fabricated by the modification of PW₁₂@TiO₂-Si(Et)Si with pyridine boronic acid via a solvothermal method. The covalent interactions between the boronic acid group of the hybrid and the glycosylated site of proteins provide the as-prepared hybrid with favorable adsorption performance towards glycoproteins. The adsorption behaviors of glycoproteins onto the hybrid fit well with the Langmuir model, and the adsorption capacities for glycoprotein IgG and Trf are high, up to 348.5 mg g^-1 and 262.6 mg g^-1, respectively. Thus, a protocol for the depletion of high abundant glycoproteins from human plasma is proposed. The percentage contents of Trf, IgG, haptoglobinis and IgM are reduced from 7.38%, 5.5%, 3.01% and 1.02% to 0.951%, 4.7%, 0.126% and 0.76%, respectively. 85 low abundant proteins are identified from the raw plasma after the depletion of the high abundance proteins, demonstrating the potential of PW₁₂@TiO₂-Si(Et)Si/Pba hybrid in proteomic studies.

Nanoparticle-supported polymer brushes for temperature-regulated glycoprotein separation: investigation of structure-function relationship

In this work, we synthesized a series of nanoparticle-supported boronic acid polymer brushes for affinity separation of glycoproteins. Polymer brushes were prepared by surface-initiated atom transfer radical polymerization of glycidyl methacrylate and N-isopropylacrylamide, followed by stepwise modification of the pendant as well as the end functional groups to introduce boronic acid moieties through a Cu(i)-catalyzed alkyne-azide cycloaddition reaction. We investigated the impact of the polymer structure on glycoprotein binding under different pH and temperature conditions, and established new methods that allow glycoproteins to be more easily isolated and recovered with minimal alteration in solvent composition. Our experimental results suggest that for the separation of glycoproteins, terminal boronic acids located at the end of polymer chains play the most important role. The thermo-responsibility of the new affinity adsorbents, in addition to the high capacity for glycoprotein binding (120 mg ovalbumin per g adsorbent), provides a convenient means to realize simplified bioseparation not only for glycoproteins, but also for other carbohydrate-containing biological molecules.

Branched polyethyleneimine-assisted boronic acid-functionalized silica nanoparticles for the selective enrichment of trace glycoproteins

Boronate affinity materials have attracted more and more attention in extraction, separation and enrichment of glycoproteins due to the important roles that glycoproteins take on in recent years. However, conventional boronate affinity materials suffer from low binding affinity mainly because of the use of single boronic acids. This makes the extraction of glycoproteins of trace concentration become rather difficult or impossible. Here we present a novel boronate avidity material, polyethyleneimine (PEI)-assisted boronic acid-functionalized silica nanoparticles (SNPs). Branched PEI was applied as a scaffold to amplify the number of boronic acid moieties. While 3-carboxybenzoboroxole, exhibiting high affinity and excellent water solubility toward glycoproteins, was used as an affinity ligand. Due to the PEI-assisted synergistic multivalent binding, the boronate avidity SNPs exhibited strong binding strength toward glycoproteins with dissociation constants of 10^-7 M, which was the highest among reported boronic acid-functionalized materials that can be applied for glycoproteomic analysis. Such a high avidity enabled the selective extraction of trace glycoproteins as low as 0.4 pg/mL. This feature greatly favored the selective enrichment of trace glycoproteins from real samples. Meanwhile, the boronate avidity SNPs was tolerant of the interference of abundant sugars. In addition, the PEI-assisted boronate avidity SNPs exhibited high binding capacity and low binding pH. The feasibility for practical applications was demonstrated with the selective enrichment of trace glycoproteins in human saliva.

Boronic acid-functionalized iron oxide magnetic nanoparticles via distillation–precipitation polymerization and thiol–yne click chemistry for the enrichment of glycoproteins

Synthesis of phenylboronic acid functionalized iron oxide nanoparticles for glycoprotein enrichment via distillation–precipitation polymerization combined with thiol–yne click chemistry.

Hyper-Cross-Linked Polypyrene Spheres Functionalized with 3-Aminophenylboronic Acid for the Electrochemical Detection of Diols

A sensor for the determination of diols using 3-aminophenylboronic acid (APBA)-functionalized hyper-cross-linked polypyrene (PPy) (APBA@PPy) is presented. The uniform (∼1 μm in diameter) and highly porous (628 m2 g-1 in specific surface area) PPy spheres are fabricated via a one-pot protocol that consists of ZnBr2-catalyzed alkylation of pyrene, a subsequent cross-linking reaction, and concomitant self-assembly. The PPy spheres formed within a few minutes at mild conditions are featured by an excellent structural integrity and inertness to organic solvents. Thus, the APBA@PPy composites (∼1 μm in diameter; 458 m2 g-1 in specific surface area) are prepared simply by substituting unreacted bromomethyl groups on the surface of PPy spheres for APBA. The APBA@PPy composites are successfully applied for the electrochemical sensing of d-glucose and dopamine. A dye displacement assay is also performed using alizarin red dye conjugated to boronic acid in glucose buffer solution.

One-step functionalization of magnetic nanoparticles with 4-mercaptophenylboronic acid for a highly efficient analysis of N-glycopeptides

A very simple and amazing approach was proposed to synthesize MPBA functionalized magnetic nanoparticles via the interaction between Fe and SH, and the as-prepared nanoparticles were successfully applied for the efficient analysis of glycopeptides in complex bio-samples with sensitivity and selectivity.

Boronic Acid-Modified Magnetic Fe3O4@mTiO2 Microspheres for Highly Sensitive and Selective Enrichment of N-Glycopeptides in Amniotic Fluid

Although mesoporous materials and magnetic materials are used to enrich glycopeptides, materials sharing both mesoporous structures and magnetic properties have not been reported for glycopeptide analyses. Here we prepared boronic acid-modified magnetic Fe₃O₄@mTiO₂ microspheres by covalent binding of boronic acid molecules onto the surfaces of silanized Fe₃O₄@mTiO₂ microspheres. The final particles (denoted as B-Fe₃O₄@mTiO₂) showed a typical magnetic hysteresis curve, indicating superparamagnetic behavior; meanwhile, their mesoporous sizes did not change in spite of the reduction in surface area and pore volume. By using these particles together with conventional poly(methyl methacrylate) (PMMA) nanobeads, we then developed a synergistic approach for highly specific and efficient enrichment of N-glycopeptides/glycoproteins. Owing to the introduction of PMMA nanobeads that have strong adsorption towards nonglycopeptides, the number of N-glycopeptides detected and the signal-to-noise ratio in analyzing standard proteins mixture both increased appreciably. The recovery of N-glycopeptides by the synergistic method reached 92.1%, much improved than from B-Fe₃O₄@mTiO₂ alone that was 75.3%. Finally, we tested this approach in the analysis of amniotic fluid, obtaining the maximum number and ratio of N-glycopeptides compared to the use of B-Fe₃O₄@mTiO₂ alone and commercial SiMAG-boronic acid particles. This ensemble provides an interesting and efficient enrichment platform for glycoproteomics research.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2011-2012

This review is the seventh update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2012. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, and fragmentation are covered in the first part of the review and applications to various structural types constitute the remainder. The main groups of compound are oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:255-422, 2017.

Nanotechnology in Glycomics: Applications in Diagnostics, Therapy, Imaging, and Separation Processes

This review comprehensively covers the most recent achievements (from 2013) in the successful integration of nanomaterials in the field of glycomics. The first part of the paper addresses the beneficial properties of nanomaterials for the construction of biosensors, bioanalytical devices, and protocols for the detection of various analytes, including viruses and whole cells, together with their key characteristics. The second part of the review focuses on the application of nanomaterials integrated with glycans for various biomedical applications, that is, vaccines against viral and bacterial infections and cancer cells, as therapeutic agents, for in vivo imaging and nuclear magnetic resonance imaging, and for selective drug delivery. The final part of the review describes various ways in which glycan enrichment can be effectively done using nanomaterials, molecularly imprinted polymers with polymer thickness controlled at the nanoscale, with a subsequent analysis of glycans by mass spectrometry. A short section describing an active glycoprofiling by microengines (microrockets) is covered as well.

New Opportunities and Challenges of Smart Polymers in Post-Translational Modification Proteomics

Protein post-translational modifications (PTMs), which denote covalent additions of various functional groups (e.g., phosphate, glycan, methyl, or ubiquitin) to proteins, significantly increase protein complexity and diversity. PTMs play crucial roles in the regulation of protein functions and numerous cellular processes. However, in a living organism, native PTM proteins are typically present at substoichiometric levels, considerably impeding mass-spectrometry-based analyses and identification. Over the past decade, the demand for in-depth PTM proteomics studies has spawned a variety of selective affinity materials capable of capturing trace amounts of PTM peptides from highly complex biosamples. However, novel design ideas or strategies are urgently required for fulfilling the increasingly complex and accurate requirements of PTM proteomics analysis, which can hardly be met by using conventional enrichment materials. Considering two typical types of protein PTMs, phosphorylation and glycosylation, an overview of polymeric enrichment materials is provided here, with an emphasis on the superiority of smart-polymer-based materials that can function in intelligent modes. Moreover, some smart separation materials are introduced to demonstrate the enticing prospects and the challenges of smart polymers applied in PTM proteomics.

Glycoproteins functionalized natural and synthetic polymers for prospective biomedical applications: A review

Glycoproteins have multidimensional properties such as biodegradability, biocompatibility, non-toxicity, antimicrobial and adsorption properties; therefore, they have wide range of applications. They are blended with different polymers such as chitosan, carboxymethyl cellulose (CMC), polyvinyl pyrrolidone (PVP), polycaprolactone (PCL), heparin, polystyrene fluorescent nanoparticles (PS-NPs) and carboxyl pullulan (PC) to improve their properties like thermal stability, mechanical properties, resistance to pH, chemical stability and toughness. Considering the versatile charateristics of glycoprotein based polymers, this review sheds light on synthesis and characterization of blends and composites of glycoproteins, with natural and synthetic polymers and their potential applications in biomedical field such as drug delivery system, insulin delivery, antimicrobial wound dressing uses, targeting of cancer cells, development of anticancer vaccines, development of new biopolymers, glycoproteome research, food product and detection of dengue glycoproteins. All the technical scientific issues have been addressed; highlighting the recent advancement.

Rapid fabrication of functionalized plates for peptides, glycopeptides and protein purification and mass spectrometry analysis

A rapid and simple approach for fabricating a disposable functionalized membrane on matrix-assisted laser desorption ionization (MALDI) targets, glass, or plastic substrates, without using complex mechanical protocols or chemical reactions, was developed for sample enrichment and mass spectrometry analysis. By coating functionalized-silica particles on a polydimethylsiloxane (PDMS)-coated plate, these particles can form a monolayer of materials on the PDMS membrane for sample handling without peeling off. An octadecyl(C18)-functionalized plate was fabricated by coating porous C18-silica particles on a PDMS-coated plate. The C18 particle-coated PDMS plate (CP plate) has better sensitivity than C18 tips and magnetic nanoparticles, along with a higher sample recovery (64.3 ± 4.9%) compared to the C18 tip method, when analyzing trace amounts of 5 fm BSA digest samples. The CP plate shows significantly higher urea/SDS removal efficiency on the cell lysate proteome compared to C18 tips. The capacity of the C18 spot (∼2.8 mm in diameter) on the CP plate was ∼10 μg of BSA digests. A hydrophilic particle-coated PDMS plate was also fabricated and successfully used for glycopeptide enrichment and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis.

Branched polyethyleneimine-assisted boronic acid-functionalized magnetic nanoparticles for the selective enrichment of trace glycoproteins

Boronate affinity materials, as efficient sorbents for extraction, separation and enrichment of glycoproteins, have attracted more and more attention in recent years.

Determination of Glycoproteins by a Self-Assembled 4-Mercaptophenylboronic Acid Film on a Quartz Crystal Microbalance

Glycosylation plays an important part in many biological processes. However, many glycoproteins are either of low abundance or covered by other components in biological samples. Hence, developing new methods to measure the glycoproteins with both high efficiency and low detection limit is important. In this work, a self-assembled 4-mercaptophenylboronic acid film was coated on a quartz crystal microbalance chip. By optimizing the reaction time and the concentration of 4-mercaptophenylboronic acid, a sensor that specifically responded to glycoproteins was created. Then, several parameters for the prepared sensor were investigated and the working curve for representative glycoprotein-transferrin was established. The linearity range was from 50 to 400 ng/mL and the detection limit was 21.0 ng/mL. The sensor was used to detect transferrin in artificial urine samples. This sensor has a low detection limit of glycoproteins requiring only a small amount of samples, and thus has potential applications in both pharmaceutical and medical areas.

Synthesis of Zwitterionic Polymer Particles via Combined Distillation Precipitation Polymerization and Click Chemistry for Highly Efficient Enrichment of Glycopeptide

Because of the low abundance of glycopeptide in natural biological samples, methods for efficient and selective enrichment of glycopeptides play a significant role in mass spectrometry (MS)-based glycoproteomics. In this study, a novel kind of zwitterionic hydrophilic interaction chromatography polymer particles, namely, poly(N,N-methylenebisacrylamide-co-methacrylic acid)@l-Cys (poly(MBAAm-co-MAA)@l-Cys), for the enrichment of glycopeptides was synthesized by a facile and efficient approach that combined distillation precipitation polymerization (DPP) and "thiol-ene" click reaction. In the DPP approach, residual vinyl groups explored outside the core with high density, then the functional ligand cysteine was immobilized onto the surface of core particles by highly efficient thiol-ene click reaction. Taking advantage of the unique structure of poly(MBAAm-co-MAA)@l-Cys, the resulting particles possess remarkable enrichment selectivity for glycopeptides from the tryptic digested human immunoglobulin G. The polymer particles were successfully employed for the analysis of human plasma, and 208 unique glycopeptides corresponding to 121 glycoproteins were reliably identified in triple independent nano-LC-MS/MS runs. The selectivity toward glycopeptides of these particles poly(MBAAm-co-MAA)@l-Cys is ∼2 times than that of the commercial beads. These results demonstrated that these particles had great potential for large-scale glycoproteomics research. Moreover, the strategy with the combination of DPP and thiol-ene click chemistry might be a facile method to produce functional polymer particles for bioenrichment application.

Bioinspired Saccharide-Saccharide Interaction and Smart Polymer for Specific Enrichment of Sialylated Glycopeptides

Abnormal sialylation of proteins is highly associated with many major diseases, such as cancers and neurodegenerative diseases. However, this study is challenging owing to the difficulty in enriching trace sialylated glycopeptides (SGs) from highly complex biosamples. The key to solving this problem relies strongly on the design of novel SG receptors to capture the sialic acid (SA) moieties in a specific and tunable manner. Inspired by the saccharide-saccharide interactions in life systems, here we introduce saccharide-based SG receptors into this study. Allose (a monosaccharide) displays specific and pH-sensitive binding toward SAs. Integrating allose units into a polyacrylamide chain generates a saccharide-responsive smart copolymer (SRSC). Such design significantly improves the selectivity of SA binding; meanwhile, this binding can be intelligently triggered in a large extent by solution polarity and pH. As a result, SRSC exhibits high-performance enrichment capacity toward SGs, even under 500-fold interference of bovine serum albumins digests, which is notably higher than conventional materials. In real biosamples of HeLa cell lysates, 180 sialylated glycosylation sites (SGSs) have been identified using SRSC. This is apparently superior to those obtained by SA-binding lectins including WGA (18 SGSs) and SNA (22 SGSs). Furthermore, lactose displays good chemoselectivity toward diverse disaccharides, which indicated the good potential of lactose-based material in glycan discrimination. Subsequently, the lactose-based SRSC facilitates the stepwise isolation of O-linked or N-linked SGs with the same peptide sequence but varied glycans by CH3CN/H2O gradients. This study opens a new avenue for next generation of glycopeptide enrichment materials.